Daily quests are a number of assignments given to players every day, for the completion of which they will get valuable rewards. Such assignments can include the following:
- producing various items and resources,
- speeding up production,
- putting up buildings,
- completing orders on the Market,
- selling a certain amount of items/resources in the Shop, or
- performing certain reactions.
As a reward you can get wooden & iron chests, which contain coins, crystals and special items, such as wooden beams & scaffolding. You have 24 hours to complete all quests for the day; after it, your list of daily quests will be updated and your previous progress reset.
You can always check your progress on daily quests by tapping on the daily quest timer at the top of the quest icon list on the left of the screen. Another way would be going to the Town Hall and tapping on the chest icon there.